Spectrofluorimetric Method for the Determination of Rhodamine B in Syrup

The rhodamine B has been used as a textile colorant. Its use in food is strictly prohibited because of its ability to form carcinogenic compounds. This study describes a method for determining rhodamine B in syrup by a fluorescence spectrophotometry. The method was validated by determining linearity, range, limit of detection, limit of quantitation, precision, and recovery. Five red syrup samples were collected from markets in Purwokerto city, Indonesia. A fluorescent compound was measured fluorometrically at 570 nm (λ_ex, 550 nm). Linear relationship with good correlation coefficients (0.9975) has been obtained in the range of 0.5–2.5 μg/ml, with a detection limit of 0.1436 μg/ml and a quantitation limit of 0.4787 μg/ml. The precision of the method was satisfactory; the relative standard deviation was 0.29%. The method was successfully applied to the analysis of rhodamine B in syrup with good accuracy; the recovery was 102.8%. The result showed that five syrup samples did not have rhodamine B.